JPH09118450A - Control method and device for paper feed motor in image input system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make control easy and dispense with a speed sensor by feed-back controlling a paper feed motor through extraction of black and white information on a black and white pattern roller from image information for obtaining speed change in alternative black and white patterns. SOLUTION: The reading width of a CCD 16 covers a range from the surface of paper to the surface of a black and white pattern roller 15. A control program 18 performs ON/OFF control or speed control of a DC motor 11. Paper feed motor speed detection means extracts black and white pattern information based on scanning on the surface of the roller 15 according to an image signal outputted from an image signal processing circuit 17 and detects the speed change in the white and black pattern. Paper feed motor control means outputs the change speed of the black and white pattern as the set output of rotation speed of the DC motor 11 to a current/voltage control circuit 19. The circuit 19 controls the current level or voltage level for driving the motor 11 based on the control information of ON/OFF and speed error set from the control program 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feed motor control method and a paper feed device in an image input device having a paper running system.

In an image input device such as an image scanner which has a paper feed system and scans a paper in a direction perpendicular to the paper feed direction while feeding the paper at a constant speed, the paper feed speed is kept constant. Motor control is necessary for this. The present invention therefore provides a simple paper feed motor control method and paper feed device.

[0003]

2. Description of the Related Art A paper feed motor control method used in a conventional image input apparatus will be described with reference to FIGS. FIG. 3 shows a conventional example using a pulse motor, and FIG. 4 shows a conventional example using a DC motor.

In the conventional example using the pulse motor shown in FIG. 3, 31 is a pulse motor, 32 and 33 are gears, and 34 is a gear.
Is a paper feed roller, 35 is a current control circuit, 36 is an excitation phase generation circuit, and 37 is a control program. The operation is performed as follows.

The control program 37 controls the current control circuit 35 and the excitation phase generation circuit 36 to rotate the pulse motor 31 at the target speed. The rotation of the pulse motor 31 is transmitted to the paper feed roller 34 via the gears 32 and 33, and the paper is fed. Therefore, the control program 37 sets the current value to be passed through the pulse motor 31 in the current control circuit 35,
Further, control information such as target speed, ON / OFF, slew up / through down is set in the excitation phase generation circuit 36.
Since the control system of the pulse motor is not a feedback system, slew-up / three-down control is performed to increase or decrease the rotation of the pulse motor at a constant rate up to the target speed in order to perform smooth drive control.

On the other hand, the conventional example using the DC motor shown in FIG. 4 is composed of a feedback system. In FIG. 4, 41 is a DC motor, 42 and 43 are gears, 44
Is a paper feed roller, 45 is an encoder, 46 is an F / V conversion circuit, 47 is an A / D conversion circuit, 48 is a control program,
49 is a current / voltage control circuit. The operation is as follows.

The control program 48 sets control information such as speed error ON / OFF to the current / voltage control circuit 49, and the current / voltage control circuit 49 drives the DC motor 41 based on the set control information. Control the current and voltage values. The rotation of the DC motor 41 is transmitted to the paper feed roller 44 via the gears 42 and 43, and the paper is fed. At this time, the rotation speed of the DC motor 41 is detected by the encoder 45 as a pulse repetition frequency. The output signal of the encoder 45 is input to the F / V conversion circuit 46,
Here, the pulse repetition frequency of the signal is converted into a corresponding voltage level. The output signal of the F / V conversion circuit 46 is D
It is a signal that represents the rotation speed of the C motor 41 in an analog manner, and is then converted into a digital signal by the A / D conversion circuit 47. The control program 48 compares the digital signal output from the A / D conversion circuit 47, that is, the current speed of the DC motor 41 with a predetermined target speed to obtain a speed error, and feeds it back to the current / voltage control circuit 49.

In this way, the pulse motor 31 of FIG.
Alternatively, the DC motor 41 of FIG. 4 operates so as to follow the target speed, and the paper can be fed at a constant speed.

[0009]

In the conventional example using the pulse motor shown in FIG. 3 for feeding the paper in the image input device, the circuit configuration and control for driving the pulse motor are complicated. In the conventional example using the DC motor shown in FIG. 4, the control is simple, but there is a problem that a highly accurate and expensive speed sensor such as an encoder is required.

An object of the present invention is to provide a low cost paper feed motor control method and a paper feed device which are easy to control in an image input device and do not require a highly accurate speed sensor.

[0011]

SUMMARY OF THE INVENTION The present invention eliminates the need to use a high precision encoder for speed detection while employing a DC motor as a paper feed motor of an image input device and employing a simple feedback control mechanism. Therefore, in the present invention, therefore, a black-and-white pattern roller that rotates in synchronization with the paper feed motor is provided at the image reading position, and this is scanned as an extension of the scanning of the paper at the time of image reading to detect the information of the black-and-white pattern. As with the encoder, the motor speed information is obtained with high accuracy.

FIG. 1 illustrates the principle of the present invention. FIG.
In the figure, 11 is a DC motor for paper feeding.

Reference numerals 12 and 13 are gears for transmitting the rotation of the DC motor 11 to the paper feed roller. 14 is a paper feed roller.

Reference numeral 15 is a black-and-white pattern roller provided so as to rotate in synchronization with the DC motor 11, and black-and-white patterns are alternately formed at equal intervals along the circumferential surface of the roller to form an image on the paper. It is arranged at the reading position and at least laterally of the paper feed path.

Reference numeral 16 is a one-dimensional CCD for reading an image, and the reading width covers from the paper surface to the surface of the black and white pattern roller 15. Reference numeral 17 denotes an image signal processing circuit, which performs signal processing on the image signal output from the CCD 16 such as amplification, white level correction, and A / D conversion in the same manner as a normal image input device.

Reference numeral 18 is a control program, which has a function of ON / OFF of the DC motor 11 and speed control, and a black and white pattern based on the scanning of the surface of the black and white pattern roller from the image signal output from the image signal processing circuit 17. Paper feed motor speed detection means for extracting information and detecting the change speed of the black and white pattern and the detected change speed of the black and white pattern are compared with a predetermined target speed as the rotation speed of the DC motor 11, and the difference is compared with the speed. A paper feed motor control means for setting and outputting to the current / voltage control circuit as an error is included.

A current / voltage control circuit 19 controls a current level or a voltage level for driving the DC motor 11 based on ON / OFF and speed error control information set by the control program 18.

With the structure shown in FIG. 1, the image of the paper is read using a simple black-and-white pattern roller and the existing CCD 16, and at the same time, the surface of the black-and-white pattern roller 15 is also read. That is, since the rotation speed of the DC motor 11 can be detected, the special encoder 4 as in the conventional example shown in FIG.
A similar operation function is realized without using 5.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2A is a sectional view of a mechanical portion of an image input device showing an embodiment of the present invention.

In FIG. 2A, reference numeral 21 denotes an image input device of a type capable of both fixed sheet reading and sheet feeding reading. The illustrated state is a state in which sheet feeding reading is being performed.

Reference numeral 22 is a carrier on which a reading unit is mounted. 23 is a light source. 24 is CC
It is D.

Reference numerals 25 and 25 'are paper feed rollers, which are driven by a DC motor (not shown). 26 is
It is a black and white pattern roller.

Reference numeral 27 denotes a shooter, which stacks sheets of paper on which images are to be read and feeds the sheets one by one to the carrier 22. 28 is a sheet.

Reference numeral 29 is a hopper, on which sheets of paper for which image reading has been completed are stacked. When the image of the paper 28 is read, the paper 28 is fed in the direction of the arrow by the paper feed rollers 25 and 25 ′, and when passing through the image reading position, the light of the light source 23 is emitted and reflected from the paper 28. The light enters the CCD 24 through the optical system and is converted into an image signal. FIG. 2B is a top view of the carrier 22, and CC
D24 reading width and paper width and black and white pattern roller 2
The relationship of the positions of 6 is shown.

As shown in the figure, the black-and-white pattern roller 26 is located laterally above the paper feed rollers 25 and 25 'from the paper path, and the CCD reading width is larger than the lateral width of the paper 28. At the reading position, it is possible to read up to the upper surface of the black-and-white pattern roller 26 beyond the paper width.

FIG. 2C is an explanatory view showing the relationship between the paper feed and the black and white pattern roller. The paper 28 is scanned by the CCD at a resolution of 400 DPI, that is, a scan line density, and the surface of the black-and-white pattern roller is read at each scan line. As a result, as shown in the drawing, the black and white are associated with the scan lines in the vertical direction of the paper 28. The pattern is detected. Since the scan line generation timing is constant independent of the paper feed speed, the number of scan lines included in each black-and-white pattern can be uniquely related to the paper feed speed. If the paper feeding speed is high, the number of scanning lines included in each black and white pattern is small, and if the paper feeding speed is low, the number of scanning lines included in each black and white pattern is large. Therefore, the current paper feed speed is determined and the DC motor is controlled by counting the number of scanning lines included in each black-and-white pattern or by checking the address intervals of the scanning lines corresponding to each change point of the black-and-white pattern. can do.

Since the resolution of image reading in an ordinary image input device is sufficiently high, it is possible to perform speed detection with high accuracy as good as that of the conventional encoder.

[0028]

According to the present invention, the existing CC is simply replaced with a simple black-and-white pattern roller instead of the encoder.
Since the speed of the paper feed motor can be detected with high precision by using D and the image signal processing circuit, and complicated control is not required, a high-performance image input device can be realized at low cost.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is an explanatory diagram of an image input device showing an embodiment of the invention.

FIG. 3 is an explanatory diagram of a conventional control method using a pulse motor.

FIG. 4 is an explanatory diagram of a conventional control method using a DC motor.

[Explanation of symbols]

 11 DC Motor 12, 13 Gear 14 Paper Feed Roller 15 Monochrome Pattern Roller 16 CCD 17 Image Signal Processing Circuit 18 Control Program 19 Current / Voltage Control Circuit

Claims (2)

[Claims] 1. A paper feed system having a paper feed roller using a DC motor, wherein a paper surface is scanned at a constant speed while the paper surface is scanned in a direction perpendicular to the paper feed direction to read an image. In a method of controlling a paper feed motor in an image input device, the paper runs on a black-and-white pattern roller that rotates at the image reading position in synchronization with the paper feed motor and has black-and-white pattern portions formed at regular intervals along the circumferential surface. It is provided on the side of the road, and at the time of image reading, scanning is performed so that the paper surface laterally extends, and the surface of the black and white pattern roller is read together with the image on the paper surface, and the black and white pattern roller is read from the image information. The image input device is characterized in that the black-and-white information of the surface is extracted to obtain the speed of alternating black and white, and this speed is used as the detection speed of the paper feed motor to feedback control the paper feed motor. Paper feed motor control method in a. 2. A paper feeding device in an image input device having a paper running system using a DC motor as a paper feeding motor, the paper feeding device being provided at least at a side of a paper running path at an image reading position, in synchronization with the paper feeding motor. A rotating black and white pattern roller, a paper feed motor speed detecting means for detecting the speed of the paper feed motor by extracting the image information portion of the black and white pattern roller from the image reading signal, and the detected paper feed motor speed and target speed. The difference between
A paper feed device in an image input device, comprising: a paper feed motor control unit that feedback-controls the paper feed motor according to the value of the result.